This invention relates to a compact constant tension traction device capable of developing a plurality of different tension forces, as selected by a user.
Conventional orthopedic traction apparatus used for applying tension forces to parts of the body of a patient typically includes a rather complicated and cumbersome combination of a framework, pulleys, ropes, and weights. The framework is erected over the hospital bed and conventional pulleys are attached to the framework and ropes are threaded through the pulleys. One end of each rope is attached to a part of the patient's body and the other end is attached to a weight which hangs vertically downward from the pulley. The weights may either be heavy metal discs, liquid-filled bags, or sand-filled bags. Not only is such apparatus cumbersome, but also it is unsightly, difficult and time consuming to assemble and disassemble, and difficult to store because of the bulkiness. In addition it is difficult to either move a patient about or for the patient to move himself while undergoing traction with such apparatus.
There have been proposed a number of arrangements which would obviate the need for the combination of pulleys, ropes and weights. Some of such arrangements are disclosed in U.S. Pat. Nos. 3,060,929, 3,085,768, 3,153,411 and 3,683,900. These references all disclose devices which utilize constant tension spring elements for producing tension forces for holding in place limbs or other parts of the body of a patient. Although the devices disclosed are more compact and apparently more convenient for use than the pulley, rope and weight arrangements, one problem which is common to these devices is the rapid, "snap back" retraction of tension cables which would result if the cables are inadvertently released. For example, if a tension cable slipped loose from its support position, it might be rapidly drawn toward the device housing and possibly cause an injury to persons or damage to the device.